Fixed problem with parallel make (-j) caused by the previous change

Fixed problem with parallel make (-j) caused by the previous change

If compilation was invoked as make -j, pass serialization didn't work.
In other words, it was possible that, for example, some library-pass
targets was made before all include-pass targets was finished. This
meant all include files were not available for compilation of libraries.

This behavior was caused the fact that recently introduced <pass>-XXX-subdir
targets was direct dependencies of <pass>. Since pass serialization is
done by putting one pass as dependency of another pass, this
serialization dependencies was on the "same level" as -subdir
dependencies and make -j executed them in parallel.

This was fixed by adding another target called <pass>-submakes which is
called recursively from <pass> target after all "serialization
dependencies" are processed. All -subdir targets are dependencies of
only -submakes target and hence are not intermixed with serialization
dependencies.

To avoid overhead caused by this additional recursive make invocation,
all recursive makes are invoked directly with the new -submakes target
as their goal. Hence, the original pass target is called only in the
top-level make.

This change can influence some "nonstandard" constructs used sometimes
in Makefile.omk that count upon invocation of the original pass in every
directory. This issue will be solved by upcoming patches.

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